Apparatus for continuously centering a moving strip



Feb. 4, 1958 E. T. LORIG 2,822,169

APPARATUS FOR CONTINUOUSLY CENTERINGA MOVING STRIP Filad Feb. 1, 1955 4 ShBBtS-ShGQt 1 Feb. 4, 1958 1 E. T. LORIG 2,822,169

APPARATUS FOR CONTINUOUSLY CEN'I'EHING A MOVING STRIP Filed Feb. 1. 1955 4 Sheets-Sheet 2 [mentor- [flm/vf ZOE/6,

1/3 War/lg E. T. LORIG Feb. 4, 1958 APPARATUS FOR CONTINUOUSLY CENTERING A MOVING STRIP 4 Sheets-Sheet 4 Filed Feb. 1, 1955 PURE- United States PatentO APPARATUS FOR CONTINUUUSLY CEN'I'ERING A MOVING STRIP Edwin T. Lorig, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of he .iersoy Application February 1, 1955, Serial No. 435,562

Claims. (Cl. 271--2.6)

tracking the strip properly has plagued industry fort many years. The different types of strip shape or contour variances and their effect on tracking will not be described here in detail since they are well known to the operator. Camber, edge wave and buckle commonly appear in the strip in various combinations. Change in temperature of the strip passing through the processing line increases the problem. Such processing lines generally have mechanical loopers or looping pits for free hanging loops to take up and provide slack at each end or the line. Free hangtag loops of comparatively great depth invariably cause trouble at high operating speeds because the strip in the loop twists and turns first one way and then the other with an action that at times becomes extremely violent. Increased tension on the strip passing through the line has been resorted to in order to improve tracking, but the tension cannot be increased above their present limits Without causing damage to the equipment and strip. There has been a tendency to increase strip speed and length of lines in order to efl'ect economics in equipment and operating costs, but this increased speed and longer lines increase lateral weaving and lateral divergence and usually requires additional looping pits with exit guides. Thus it is seen that the problem of proper tracking is a very important and dilfieult one. 'i he self-centering rolls disclosed in my Patents Nos. 2,593,157. 2,593.58 and 2,592,581, all dated April 15. i952, have accomplished much in improving the tracking of strip through processing lines. Further advances have been made by the use of the apparatus disclosed in my copending application, Serial No. 284,379, filed April 25, 1952, now Patent No. 2,706,625, dated April 19, 1955. However, in some instances, when handling strip of very poor transverse and longitudinal shape at high speeds the centering ability of the equipment described above is not great enough to overcome the lateral weaving.

In centering strip in the form of an endless belt the same or similar problems are involved. Belts which are supposed to be duplicates actually vary in dimensions and they do not have straight edges or the same longitudinal contour. One edge is usually shorter than the other. Either or both edges may be crooked. When the apparatus is adjusted in such a manner that one particular belt will center when placed on the rolls in a particular manner the belt will not center without further adjust ment when turned end for end. if a new belt is substituted 2,822,169 Patented Feb. 4, 1958 for the old further adjustment is necessary in practically all instances in order to track the belt satisfactorily.

It is therefore an object of my invention to provide a roll assembly having the ability to properly track strip either in a processing line or in the form of an endless belt.

Another object is to provide a strip processing line for handling strip at high speeds with a minimum of lateral weaving and divergence.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Figure l is a schematic view of the roll assembly of my invention;

Figure 2 is a view taken on the line IIII of Figure I;

Figure 3 is a view taken on the line Ill-Ill of Figure 1;

Figure 4 is a schematic view of a tight strip processing line;

Figure 5 is a schematic view of a strip processing line having a looper pit therein;

Figure 6 is a view, similar to Figure 1, showing a modification of my invention;

Figure 7 is a view, similar to Figure 3, showing another type of roll;

Figure 3 is a schematic plan view of an endless belt arrangement utilizing my invention;

Figure 9 is a side elevation of the arrangement shown in Figure 8; and

Figure 10 is a view taken on the line X-X of Figure 9.

Referring more particularly to Figures 1 to 3 or" the drawings the reference numeral 2 indicates a narrow bodied roll around which strip S passes. From the roll 2 the strip S passes around a self-centering roll 4 and then around a second narrow bodied roll 6. As shown in Figure 2 the narrow bodied rolls 2 and 6 are identical and have a cylindrical strip supporting surface 8 of considerably less width than the strip S. The rolls 2 and 6 are supported for rotation in axially aligned spaced bearings 10. in some instances an extension 12 is provided on the roll shaft 14 to provide a driving connection to rotate the roll. In other instances the rolls 2 and 6 will be idler rolls rotated by strip Contact only. For very severe operating conditions the narrow bodied rolls 2 and 6, instead of being solid rolls, will be self-centering rolls of the type disclosed in my above mentioned patents. For example, the rolls may be hollow rolls split on their transverse centers 16 as shown in my Patent No. 2,593,158. Roll 4 is n self-centering roll of the type disclosed in my above mentioned patents. The particular roll shown in Figure 3 consists of a straight shaft 18 having two sub stantially cylindrical roll sections 20 supported thereon and mounted for rotation with the shaft by means of collars 22 fastened to the shaft, each collar having a pin 24 thereon extending into a hole 26 in the end of the adjacent roll section. The shaft 13 is mounted for rotation on axially aligned bearings 27 and may be provided with a drive extension 28. All the self-centering rolls discussed above have roll sections on opposite sides of the transverse center of the roll which roll sections rotate at the same angular velocity and uhich are so constructed that an axial force directed inwardly toward the transverse center of the roll is provided at the points of contact with the strip, thus tending to keep the strip on center regardless of outside forces. The spacing of the rolls 2. 4 and 6 may vary but it is desirable to have the roll 2 on the approach side of roll 4 spaced a considerable distance from the roll 4 and the roll 6 fairly close to the roll 4. When the roll assembly is used in reversible processing lines the roll 4 will preferably be equidistant from the rolls 2 and 6. The strip must pass around a considerable are of each of the rolls and preferably should pass around at least 90 of the roll if possible. For best results one side of the strip contacts one roll and the opposite side of the next succeeding roll as shown in Figure l. However, the strip may approach roll 2 and leave roll 6 from the bottom and be mapped around these rolls in a counterclockwise direction instead of clockwise as shown. The roll assembly described acts to center and align the strip on the roll 4 regardless of normal shape variances. The centering and aligning efiects on the strip are reflected a considerable distance in both directions from the roll t. it should be observed that the solid narrow bodied rolls have no centering ability in themselves but do have the ability to slightly distort and change the planes in the moving strip in the proper direction to combine with the centering effect of the self-centering roll to maintain suitable strip edge alignment. The particular roll shown in Figure 3 increases the tension slightly on one edge of the strip and decreases it on the other as slight lateral movement of the strip occurs, thus causing the succeeding roll on the delivery side to tilt the strip edges automatically in the proper direction to secure recentering and alignment of the strip.

Figure 4, shows a typical strip processing line which utilizes the roll assembly of my invention and which does not require edge guides. This line may be termed a tight ine since the strip is under tension throughout the line and no looper pits are utilized. The strip S pases from an unwinding reel 30 around a narrow bodied rubber covered self-centering roll 32 preferably of the type shown in my Patent No. 2,592.58l. From the roll the strip passes around rolls 34 and 36 to the processing equipment 38. The roll 34 is a self-centering roll preferably of the type shown in Figure 3 and the roll 36 is a narrow bodied solid roll. It will be seen that the rolls 33, 34 and .16 constitute a roll assembly as shown in Figure It. in the processing equipment the strip S passes around rolls 40 which are preferably narrow bodied rolls. However, the upper rolls may be self-centering rolls in which case they form with the narrow bodied rolls additional center ing roll assemblies. From the processing equipment 38 the strip passes around a narrow bodied roll 42 and hence to and around a self-centering roll 44 preferably oi the type shown in Figure 3. The strip S then passes to the tension bridle 46 consisting of rolls 48, 59, 52. 54 and 56. The rolls 48 and 52 are narrow bodied self-centering rolls of the type shown in my Patent No. 2,592,581 and the rolls 50 and 54 are full width rolls of the type shown in my Patent No. 2,592.581. It is preferred to have the rolls 48, 50. 52 and 54 constructed with slits as shown in my copcnding application, Serial No. 380,646. filed Septemer 17. 1953, now Patent No. 2,772,879, instead of with he comparatively wide grooves shown in the patent. The roll 56 is a plain cylindrical roll and may be omitted 51 desired. l have found that rolls of the type shown in my Patent No. 2.592.,58l operate very satisfactorily in drip processing lines when used as bridle or pinch rolls, es ecially when modified as described above. The rolls 42.. 44 and t?! constitute a roll assembly of the type shown n Figure i. From the roll 54 the strip passes around a .nrlt-ccntcring roll. 58 which may be either a full bodied or jlJll'Olv' bodied roll similar to rolls 48 or 50. The strip S then passes to the winding reel 60. In strip processing lines it is preferred that each roll have a strip wrap of at least 90" and that opposite sides of the strip contact successive rolls. All of the rolls are preferably either narrow hodicd cylindrical solid rolls or self-centering rolls. The strip 8 is preferably under low tension between the unwinding recl and the bridle rolls, under medium tension in the bridle rolls and under high tension between the tension bridle and the winding reel so as to produce a tightly wound coil. The line shown in Figure 4 may be provided with mechanical loopers or free hanging loops in looper pits arranged in the usual manner.

Figure 5 shows an arrangement of a looper pit in a processing line which permits use of a looper pit without the disadvantages mentioned above. The strip S passes from an uncoiler 62 around a self-centering roll 64, preferably of the type shown in my Patent N0. 2,592,58l, through the processing equipment 66 and then over and around a sell-centering roll 68 preferably of the type shown in my Patent No. 2,593,157, then down around a narrow bodied roll 70, up and around a self-centering roll 73, precrahly of the same type as roll. 68. and then down around it narrow bodied rubber covered centering roll 74 or the type shown in my Patent No. 2,592,581. The rolls 7t), 72 and 7-; constitute a centering roll assembly. A full bodied rubber covered centering roll 76 is arranged above m l 74 in inch roll arrangement therewith and the strip passes lhercaround. The strip S then forms a free hanging loop 78 having the roll 76 as one support and a self-centering roll 30 as the other support. From the roll 30 the strip passes down around narrow bodied roll 82 and up around self-centering roll 84 and then down and around bodied rubber covered centering roll 86. The rolls and 84 are preferably of the type shown in my Patent No. 2,593,157. The rolls 82, 84 and 86 form a centering roll assembly. The roll 86 together with rolls SB, 90 and 92. form a tension bridle. The rolls 88 and 92 are full bodied rubber covered centering rolls and the roll 90 is a narrow bodied rubber covered centering roll having slits therein. The strips 5 passes from the rolls 9?. around a roll 94 to a winding reel. 96. The roll 94 may be either a rubber covered centering roll or a narrow bodied roll. The distance between rolls 76 and 80 should be suificiently long for the catcnary loop 78 to provide sufiicient strip tension and flatness at the bottom to prevent the twisting and tangling action referred to above. It will be understood that additional looper pits may be provided in the line if necessary.

I have also found that very satisfactory centering characteristics can be provided even though roll 2 is mitted in the roll assembly of Figure 1. In other words, shown in Figure 6 the strip S passes first over a selfcentering roll and then under a roll 102 which is substantially parallel thereto. In the case of steel strip the roll 102 must be narrow bodied but when handling material more elastic than steel, such as leather, the roll may be either crowned or narrow bodied. The roll llii) may be constructed as in Figure 3 or may be constructe' as shown in Figure 7. The roll of Figure 7 is of the general type shown in my Patent No. 2,593,157, and consists of two roll sections 104 rotatably mounted on a bent shaft 106. The ends of the shaft 106 are stationarily mounted in supports 108. Means such as pins 110 extending between the sections 104 are provided for rotating the roll sections in unison. Other types of selfcentering rolls such shown in my Patent No. 2,592,581 may also be used. in any case the roll preferabiy dillers from the patented rolls in that it is provided with a hollow center. Thus, only a small portion of the edges or the strip lightly contact the roll at spaced points 111 and I12. The strip S is preferably wrapped around an arc of approximately 45 of the roll 100. It will be seen that the strip when passing over the rolls 10d and 1512 will contact the roll 1011 at two points and the roll 102 at one point which is located approximately at the center of the strip. This arrangement provides for fast and accurate centering of the strip and is suitable for such purpose in any processing or strip handling equipment. From the roll 162 the strip may pass over a narrow bodied roll 114. The operation of the roll assembly when using a narrow bodied roll is essentially the same as when using a crowned roll and is especially advantageous when operating under low strip tensions. In some instances, especially when using a narrow bodied roll, the selt-centering roll 100 need not have a hollow center.

Figures 8, 9 and 10 show a further embodiment of my invention as applied to a strip in the form of an endless belt B. In this embodiment a belt 8 passes around pulleys or rolls 120, 122, 124 and 126. Roll 120 is mounted on a rigid U-shapcd yoke 128 which is pivotally mounted about a knife edge pivot 130 at each end. An arm 132 is attached to the center of the yoke and extends outwardly therefrom. Bolts 133 and 134 are attached to the machine frame 136. Bolt 133 passes through aligned holes in the yoke 128 and arm 132. Bolt 134 extends upwardly through a hole in the free end of arm 132. A spring 138 surrounds the bolt 134 and is confined between the arm 132 and nut 140 so that the arm 132 is biased downwardly at all times to provide a desired tension to the belt B. The holes for the bolts 133 and 134 are slightly larger than the bolts to permit slight tilting of the yoke. If desired a counterweight can be substituted for the spring tension means. The roll 120 is shown as a self-centering roll of the general type shown in my Patent No. 2,593,157 but has a specific contour. If desired the roll may be of the type shown in my Patents Nos. 2,592,581 or 2,593,158. Each half of the roll 120 has a cylindrical section or portion 142 adjacent the center thereof, a conical section or portion 144 adjacent thereto which decreases in diameter away from the cylindrical portion and a conical section or portion 146 adjacent bearings 147 which increases in diameter away from the conical portion 144. The width of the belt B is preferably slightly greater than the distance between the small diameter ends of the conical sections 144. The diameter of sections 142 is approxi mately equal to the maximum diameters of sections 146, that is, it may be exactly equal to or slightly greater or less in diameter than said sections. The amount of taper of the conical portions 144 and 146 is greatly exaggerated for the purpose of illustration. In most instances the difference in radius is only a matter of a few thousandths of an inch. The rolls 122 and 126 are cylindrical narrow bodied rolls and the roll 124 may be either a narrow bodied or full bodied cylindrical roll. The roll 120 may be substituted for the selfcentering roll 4 in the roll assembly shown in Figure l in combination with either one or two narrow bodied rolls. The use of this particular type roll gives a stronger centering action than when using the rolls shown in Figures 3 or 7. The combination disclosed is particularly suited for flexible belts and the exact point of contact of the belt on the roll 120 depends upon the tension applied by means of the spring 138. However, it will be seen that the belt does not contact the center of the roll so that there is no danger of the belt being marked by the parting in the roll.

While several embodiments of my invention have been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A self-centering roll for centering and aligning strip passing thereover comprising two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, each section of said roll having a cylindrical portion adjacent the transverse center, a first conical portion adjacent said cylindrical portion having a decreasing diameter away fromthe cylindrical portion, and a second conical portion adjacent said first conical portion having an increasing diameter away from said first conical portion, the maximum diameter of said second conical portion being approximately the same as the diameter of the cylindrical portion, the width of said strip being at least as great as the distance between the junctions of the first and second conical portions.

2. A roll assembly for automatically centering a moving strip comprising a self-centering roll around which the strip passes, said self-centering roll having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, each section of the self-centering roll having a cylindrical portion adjacent the transverse center, a first conical portion adjacent said cylindrical portion having a decreasing diameter away from the cylindrical portion and a second conical portion adjacent said first conical portion having an increasing diameter away from said first conical portion, the maximum diameter of said second conical portion being approximately the same as the diameter of the cylindrical portion, the width of said strip being at least as great as the distance between the junctions of the first and second conical portions, and a second roll arranged in tandem with said self-centering roll on the exit side thereof and around'an arc of which the strip passes, said second roll having a cylindrical strip supporting surface of considerably less width than the width of the strip.

3, A roll assembly for automatically centering a moving strip comprising a pair of spaced apart narrow-bodied rolls arranged with their axes substantially parallel, each of said rolls having a substantially cylindrical strip supporting surface of less width than the width of the strip, and a self-centering roll mounted between said narrowbodied rolls substantially parallel thereto, said self-centering roll having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, each section of the self-centering roll having a cylindrical portion adjacent the transverse center, a first conical portion adjacent said cylindrical portion having a decreasing diameter away from the cylindrical portion and a second conical portion adjacent said first conical portion having an increasing diameter away from said first conical portion, the maximum diameter of said second conical portion being approximately the same as the diameter of the cylindrical portion, the width of said strip being at least as great as the distance between the junctions of the first and second conical portions, the strip passing around a substantial arc of one of said narrow-bodied rolls, then around a substantial arc of the self-centering roll and then around a substantial arc of the other of said narrowbodied rolls.

4. Apparatus for automatically centering a moving endless strip comprising a self-centering roll around which the strip passes, said self-centering roll having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, each section of the self-centering roll having a cylindrical portion adjacent the transverse center, a first conical portion adjacent said cylindrical portion having a decreasing diameter away from the cylindrical portion and a second conical portion adjacent said first conical portion having an increasing diameter away from said first conical portion, the maximum diameter of said second conical portion being approximately the same as the diameter of the cylindrical portion, the width of said strip being at least as great as the distance between the junctions of the first and second conical portions, and a second roll arranged in tandem therewith, said second roll having a cylindrical strip supporting surface of considerable less width than the width of the strip around an arc of which the strip passes.

5. Apparatus for automatically centering a moving 7 endless strip comprising, a self-centering lUii around which the strip passes, said sell-centering roll having two roll sections one on each side of the transverse center of the rot] and means for rotating the roll sections at the same angular velocity, said roll sections being contructed so as to provide axial forces diructod inwardly toward the transverse center of the roll at the points of Contact with the strip, each section of the scll ccntering roll having a cylindrical portion adjacent the il'illlfiverse center, a first conical portion adjacent sniti cylindrical portion having a decreasing diameter away from the cyiindricai portion and a second conical portion adjacent said first cortical portion hating an increasing diameter away from said first conical portion, the maximum diameter of said second conical portion being a proximately the same as the diameter of the cylindrical portion, the width of said strip being at least as great as the distance between the junctions of the first and second conical portions, and a pair of narrowbodied rolls one on each side of said self-centering roll arranged with their axes substantially parallel to the self-centering roll and around which the strip passes, each of said rolls having a substantially cylindrical strip supporting surface of less width than thi. width of the strip.

References Clted in the file of this patent UNITED STATES PATENTS 2,593,157 Lorig M Apr. I5, 19521 2593,58 Lorig Apr. l5, 1952 2.665592 Lorig Jan. 12, 1954 2,7Ul,430 Lorig Feb. 8, 1955 12,706,625 Lorig Apr. 19, 1955 m mnu... t U. 5. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,822,169 February 4, 1958 Edwin T. Lorig It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Colmnn 4, line 21, after "around" insert narrow Signed and sealed this 1st day of April 1958.

(SEAL) fittest:

KARL mm ROBERT c. WATSON Atteeting Officer Comniesioner of Patents 

